The invention relates to an epitaxy reactor comprising a space containing a platform for supporting semiconductor wafers with a circulation of gas between the centre and the periphery of the platform, which space is closed by a cover which is substantially flat and is parallel to the platform during operation, while a gas-conducting crown comprises a baffle plate, which surrounds the platform and is provided with inlets regularly distributed along the periphery of the platform.
Such a reactor is discribed in the document FR-A-88 03 688 (PHF. 88514). In the reactor described in this document, the crown is a circular crown of quartz constituting a vertical baffle plate, which surrounds the platform, is provided with regularly spaced slots and is placed on the bottom of the space of the reactor.
Such a crown of a rigid material has the disadvantage that, the larger the space chosen between the crown and the cover, the greater is the possibility that gases pass through this space and leave there dirtying deposits, whereas, the narrower the space is chosen, the greater is the risk of cracking if a hard foreign body wider than the said space falls unfortunately onto the crown before the cover is pressed. There is no satisfying compromise. Of course, the use of a rubber gasket is entirely excluded in this position because of the temperature.